Danco HC660 Hydroclean Fill Valve, Saves Water, Detects Leaks, Cleans The Tank, Requires No Tools To Install, Signals When Properly Installed & Easily Calibrated For Efficient Full Flush Power, A Simple 1 Time Adjustment Allows The Customer To Calibrate The Rate At Which The Bowl Fills, Saving Up To 4 QT Of Water With Each Flush, Allows The Height Of The Valve To Be Set After Installation & Even Under Pressure.